Several organopolysiloxane rubber compositions for coating high voltage electrical insulators have been disclosed for improving the electrical characteristics of electrical insulators. For example, Niemi describes a method for preparing high voltage insulators in U.S. Pat. No. 4,476,155 in which a composition containing the product obtained by mixing a hydroxyl endblocked polydimethylsiloxane with aluminum trihydrate and a ketoxime functional silane, is applied to the outer surface of an insulator.
Adkins in U.S. Pat. No. 4,822,830 describes organopolysiloxane elastomers having improved adhesion, improved contact angle, accelerated cure rate, improved arc resistance, longer useful life, resistance to arcing and improved resistance to leakage of electrical current.